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# Questions tagged [bode-plot]

Anything related to Bode plots, i.e. a special graphical representation of the frequency response of a linear time-invariant system.

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6k views

### What are some insights from looking at Bode plots

After studying this in school, the entire concept of a Bode plot still seems to be as a bit of a let down for me given how much emphasis is placed upon it, how often this tool is rumored to be used in ...
45k views

### Gain margin and Phase Margin Physical Meaning

I have been trying to understand the physical concept of Gain and Phase Margin. What I understand about this is that a relative comparison around the critical point $(-1,0)$, which when converted ...
2k views

### Practical ways to obtain Bode plots for an unknown circuit

I want to use a practical method/way where I can obtain roughly the Bode plot of a system especially a filter. This of course can be done by using complex math or implementing the circuit in a SPICE ...
4k views

### What does a Bode plot represent and what is a pole and zero of a Bode plot?

I studied Bode plots and the author of my book is somehow relating zeros of transfer functions to Bode plots. What is the relation between zeros or poles of a Bode plot and transfer function? We ...
34k views

### Why a low-pass filter applied to a square wave gives a weird wave?

When a low-pass filter acts on a square wave, the output is something similar to this: My question is simple. If the filter is a low-pass filter, it should filter all frequencies that are above some ...
885 views

### Interpreting bode plot of type 3 compensation network for buck regulator

I'm struggling to design the type 3 compensation network for a simple buck PWM controller. The controller is a Richtek RT8110B. According to the datasheet, half of the type 3 network is in-built and ...
1k views

### Op amp circuit stability in linear regulator circuit

I am trying to design a stable linear regulator using MOSFET and op amp. Schematics is shown below: I am using LTSpice for simulations. This circuit is mostly for educational purpose: I want to ...
2k views

### Problem with Bode diagram in LTspice

I am working on a buck converter and I want to obtain the Bode diagrams of the open-loop circuit. The below circuit is what I made. However, the DC-gain is -96 dB while it should be very small around -...
945 views

### What does actually the "unravel branch wrap" option do to the phase plot in LTspice?

Below two Bode plots are identical just that in the second one the option "unravel branch wrap" is unticked for the phase plot: What does this option do to the phase plot?
14k views

### deriving the transfer function given bode plot

I have been given the following question on finding the transfer function from the following bode plot I know that the transfer function should look like this \begin{equation} H\left(jw\right)\:=\:\...
3k views

### Interpretation of mathematicial and corresponding physical meaning of gain and phase margin

In my textbook these are the definition of gain and phase margin: The gain margin is defined as the change in open-loop gain required to make the system unstable. The phase margin is ...
49k views

### What is the transfer function for a first order active high-pass filter

What is the transfer function for the below circuit? simulate this circuit – Schematic created using CircuitLab Since the op-amp has unity gain, the transfer function should be the same as a ...
1k views

### Why are there ripples in the passband of some filters, like the Chebyshev filter?

Please see the Bode magnitude plot as we steadily increase the input frequency to the filter. Why does the magnitude oscillate? What physical component(s) in the filter circuit is producing that ...
2k views

### Phase margin measured at lowest positive-gain point, rather than 0dB point?

When discussing voltage regulators, one often hears that phase margin should be measured at the 0dB gain crossing. This makes intuitive sense in a simple system where the phase has only a negative ...
2k views

### Draw Bode-Plot of a transfer function

I want to draw the bode plot of a tranfer function: $$H(j\omega)=\frac{100j\omega T}{j\omega T + 10}, T=1s$$ Now I have $$H(j\omega)=\frac{100}{1 + \frac{10}{j\omega T}}, T=1s$$ Using a double ...
1k views

### What's the meaning of a Bode Plot when talking about nonperiodic inputs?

The bode plot itself is built based on a transfer function, regardless of the input signal that will excite the circuit. Based on what I've learned, the bode plot show us how the response amplitude ...
1k views

### Pole zero plot of band reject filter

Here is a band reject filter with its transfer function and bode plot. I don't understand how the pole frequencies and zero frequencies are drawn on the bode plot. Even with the pole and zero ...
2k views

### How are the -3dB point and the pole of an op-amp related?

I have been looking at AC frequency responses for op-amps and I was wondering how an op-amp's pole and the frequency at the -3dB point are the same? They both mark the location where the gain starts ...
989 views

### Transfer function of electrical network

I need help with this problem. The transfer function that I found is ((RCS+1)/(2RCS+1)) , but then I cannot go further because the form of T.S is untypical. The typical form of this question is RC ...
2k views

### How to find the cutoff frequency of an underdamped second order low pass filter?

I've learned that for a first order low pass filter (LPF) the 3 dB frequency is one where the amp's gain is (surprise) -3 dB below the DC gain. However, on a second order LPF that is underdamped we ...
6k views

### Finding Transfer Function, Poles, Zeros of an RC Circuit

I'm trying to brush up on some electronics theory and am working through this PDF. At the bottom of page F-6 there is a problem, F.1, that I am currently trying to solve. The circuit is as follows: ...
683 views

### dc to dc converter bypass capacitor consideration

I using a TI buck regulator (LM21212) to power a bunch of components on my board at a certain voltage. When calculating stability, do I need to take into account all the decoupling capacitors (e.g. 0....
582 views

### Using an oscilloscope to measure the gain of an op-amp circuit (with capacitors)

I have an upcoming laboratory exam where we have to construct an op-amp circuit (from our experiments the circuits were always varied and probably will be a bit more difficult on our exam.) We are ...
985 views

### Phase margin is 90° but transient step response shows overshoot

The Bode plot of the loop is as shown here: The transient step response looks like this: The block diagram looks something like this - basically a single stage op-amp (OPAMP in figure) with high ...
2k views

### How can I export the frequency response from LTSPICE without phase wrapping?

After I plotted the frequency response of a circuit using LTSpice as shown: I exported the plots data as a .txt file in order to plot them after that using MATLAB, however, after I plotted the data ...
90 views

### Butterworth Filter attenuates noticeably in pass-band

The Issue: I am using a Maxim MAX7480 8th order Butterworth low-pass filter to counter any aliasing from a sensor that measures signals up to 3kHz, but I only want up to 1kHz. Thus a critical ...
1k views

### Why is frequency not measured in db in bode's plot?

While drawing bode's graph paper where Y axis is gain given in db while the X axis is frequency given in absolute value but scale used is log. I think the reason for log scale on X axis is to increase ...
1k views

### Is -3dB bandwidth defined for any type of transfer function?

If I have response like the following, is it still valid to say bandwidth of the circuit is 2.31kHz?
48k views

### Resonant Frequency from Bode plot

If we have a transfer function that shows no peaking in the magnitude bode plot (Starting from a flatline and then rolling off). Does this mean that there is no resonant frequency? Or do we consider ...
14k views

### What exactly is Pole Frequency in a Filter and how does it affect the frequency response?

I'm having great trouble understanding the concept of a pole in a real world electric circuit. I do understand what a 'pole' is and what a 'zero' is, in the point of view of a 'Transfer Function' but ...
3k views

### Transfer Function and Bode Plot from Poles and Zeroes

I've got the following bode plot from a black box: I've calculated the zero to be 1055 and pole to be 67. Thus I'm using the transfer function $H(s) = (s-1055)/(s-67)$ but this gives a clearly ...
337 views

### Finding transfer function from Bode plot

While I know how to find the transfer function from the response graph, I don't know how to find it from Bode plot. What I know about the system: The system is a second order system The system has no ...
18k views

### How do you rewrite a transfer function to standard form?

How can I rewrite a transfer function in terms of resonance frequency $\omega_0$ and damping factor Q? Referred to as "standard form" in the university materials. I'm still at it, trying to ...
733 views

### What can be inferred from the frequency an op-amp is oscillating at?

For whatever reason, I seem to create a lot of oscillators in the course of developing circuits involving op-amps. I'm wondering if the frequency of oscillation, which normally appears to be quite ...
160 views

### Bode Plot: calculating phase change

I need to plot this transfer function When plotting the phase vs frequency graph, I am having problems to calculate the change in phase between 10 and 10^1.5. To my understanding, at frequency=10 the ...
9k views

### How to determine sinusoidal steady state response from bode plot

I'm given a problem by the following: Find the sinusoidal steady state response (in the time domain) of the following systems modeled by transfer function, P(s), to the input u(t). Use the Bode plot (...
353 views

### About negative gain in Bode plot regarding the op-amp circuit design and its relationship with the feedback resistor

I am new to circuit simulation and now I am using Tina to simulate an op-amp circuit for a photodetector. I have some questions regarding the Bode plot. Below is the circuit design, based on the ...
2k views

### Transfer function and bode plot of an op-amp circuit

Given is a op-amp circuit which has to be solved using the nullor model to find the transfer function as shown below: Using the nullor model of an ideal op-amp I tried to find the transfer function ...
67 views

### Where is the origin pole in my CM buck SIMPLIS ac simulation?

I know that current mode buck regulators are generally stable as long as they're actually operating in current mode (i.e. the inductor ramp current is large enough to prevent slope compensation from ...
203 views

### How to design analogue compensation for SMPS from Bode Plots?

In a complicated switched mode power supply where the transfer function is unknown, is there a way to design an analogue controller and compensation from the bode plot alone? I am having difficulty ...
758 views

### How can a Bode plot be like that?

Can you do explain how to draw a Bode plot with GH(s)? How do I get the slope and intersection point? This is one of the teacher's examples. He drew it but I don't know what it means. Can you explain ...
1k views

### How to sketch the Bode diagram of the output filter of a Buck converter?

I'm trying to figure out the Bode diagram of the output filter of a Buck converter: simulate this circuit – Schematic created using CircuitLab Vout is ...
3k views

### What is an "origin pole"?

I'm studying Christophe Basso's book Designing Control Loops for Linear and Switching Power Supplies. In the book, he often uses the term "origin pole". This is what I think I understand about it so ...
71 views

### What is the phase margin of this inverting amplifier?

I'm having trouble finding the phase margin the telescopic cascode amplifier I'm currently building. This source says that the phase margin for an inverting amplifier is the distance from -360 degrees ...
104 views

### Why do we talk about system stability as a whole when Barkhausen criteria is valid only for one specific frequency?

The relationship AB=1 will be applicable only at a specific frequency. For instance, following is the bode plot for a circuit I have and as can be seen, the barkhausen criterion is met only at 6.3MEG ...
12k views

### Find transfer function from Bode plot

This is my Bode plot The solution manual says the function plotted is $$\frac{s^2+0.02s+1001}{s^2+2s+101)(s^2+20s+10100)}$$ What I know is the Bode plot for $$\frac{s^2+2ζω_ns+ω_n^2}{ω_n^2}$$ and the ...
2k views

### Steps to hand draw Bode magnitude plot for a particular transfer function

Can anyone guide me through how to hand draw a correct Bode magnitude plot for $$G(s) = \dfrac{48000}{s(s+0.1)(s+100)}$$ Don't even need phase plot, just need correct magnitude plot As few ...
155 views

### My bode plot does not mach with calculated cut-off frequencies

I have modelled a band-pass filter, but when I calculate the cut off-frequencies and amplitude it does not match with the bode-plot. I am not able to find out what is wrong, hope that someone might ...